2010 Cadillac CTS Sedan AWD V6-3.6L Page 524
4. Command the horns ON and OFF with a scan tool. The test lamp should turn ON and OFF when changing between the commanded states.
瀚慖f the test lamp is always OFF, test the control circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace
the BCM.
5. If the test lamp is always ON, test the control circuit for a short to ground. If the circuit tests normal, replace the BCM
6. If all circuits test normal, test or replace the HORN relay.
Component Testing
1. Ignition OFF, disconnect the HORN relay.
2. Test for 60-180 ohms between terminals 85 and 86.
瀚慖f not within the specified range, replace the relay.
3. Test for infinite resistance between the following terminals:
* 30 and 86
* 30 and 87
* 30 and 85
* 85 and 87
瀚慖f not the specified value, replace the relay.
4. Install a 30A fused jumper wire between relay terminal 85 and 12 volts. Install a jumper wire between relay terminal 86 and ground. Test for
less than 2 ohms between terminals 30 and 87.
瀚慖f greater than the specified range, replace the relay.
Repair Instructions
Perform the Diagnostic Repair Verification (See: Verification Tests) after completing the diagnostic procedure.
* Relay Replacement (Attached to Wire Harness) (See: Power and Ground Distribution/Power Distribution Relay/Service and Repair/Relay
Replacement (Attached to Wire Harness))Relay Replacement (Within an Electrical Center) (See: Power and Ground Distribution/Power
Distribution Relay/Service and Repair/Relay Replacement (Within an Electrical Center))
* Control Module References (See: Testing and Inspection/Programming and Relearning) for BCM replacement, setup, and programming
B2850
DTC B2850, B2855, B2870, or B2875
Diagnostic Instructions
* Perform the Diagnostic System Check - Vehicle (See: Testing and Inspection/Initial Inspection and Diagnostic Overview/Diagnostic System
Check - Vehicle) prior to using this diagnostic procedure.
* Review Strategy Based Diagnosis (See: Testing and Inspection/Initial Inspection and Diagnostic Overview/Strategy Based Diagnosis) for an
overview of the diagnostic approach
* Diagnostic Procedure Instructions (See: Testing and Inspection/Initial Inspection and Diagnostic Overview/Diagnostic Procedure
Instructions)provides an overview of each diagnostic category
DTC Descriptor
DTC B2850 01
- Telescope Forward Switch Circuit Short to Battery
DTC B2855 01
- Telescope Rearward Switch Circuit Short to Battery
DTC B2870 01
- Tilt Up Switch Circuit Short to Battery
DTC B2875 01
- Tilt Down Switch Circuit Short to Battery
Diagnostic Fault Information
